The present invention relates to a small type joystick, and more particularly, to the small type joystick in which engaging performance of operating shafts projected from an operating member with respect to shaft holes which are formed in both side walls defining an elongated hole of a rotary member can be maintained, and at the same time, deformation of the rotary member will be prevented.
A related small type joystick will be described referring to FIGS. 4 to 7. In the drawings, reference numeral 1 designates a small type joystick (hereinafter, simply referred to as a joystick). The joystick 1 includes arms 3, 4 as rotary members perpendicular to each other which are provided above and below in a casing 2 so as to freely rotate. These arms 3, 4 are pivotally supported by the casing 2 at their respective opposite ends, and respective one end portions of the arms 3, 4 are coupled to variable resistors 5, 6 as outputting members.
Moreover, the arms 3, 4 are formed, in respective center parts thereof, with elongated holes 7, 8 which extend in a longitudinal direction of the arms 3, 4, and an operating stick 9 as an operating member is provided so as to pass through the elongated holes 7, 8. A lower end portion of the operating stick 9 is formed to have a convex spherical face 9a, while concave spherical portion 10a is formed in a center part of a base 10 of the joystick 1 so that the convex spherical face 9a may be rotatably mounted on the concave spherical portion 10a. Further, a knob (not shown) is fitted to an upper end of the operating stick 9.
Accordingly, when the operating stick 9 is operated, the operating stick 9 rotates on the concave spherical portion 10a making it as a rotation pivot, thereby to rotate the arms 3, 4. Then, the arms 3, 4 rotate the variable resistors 5, 6 which are coupled to the arms 3, 4, and the variable resistors 5, 6 produce outputs depending on the rotation of the operating stick 9.
In addition, as shown in FIG. 5, the joystick 1 has shaft portions 11 which are laterally projected from a lower end part of the operating stick 9. The shaft portions 11 are rotatably engaged, in a manner of pin joint, in shaft holes 13 which are formed in center parts of both side walls 12 defining the elongated hole 8 of the lower arm 4, and the operating stick 9 is fixed to the arms 3, 4 in a vertical direction. Moreover, in order to hold the arms 3, 4 in neutral positions, a coil spring 15 is interposed between the base 10 and a ring-like support member 14 which has a large opening in its center part which is abutted against a lower face of the lower arm 4 and has an inverted concave shape in cross section.
In the above related small type joystick, the shaft portions projected from the lower part of the operating stick are forced to be elastically inserted into the shaft holes which are formed in the lower rotary member, and rotatably engaged therein. Therefore, especially in such a mechanism that the operating shaft and the rotary member is engaged with each other, the rotary member need to be flexed, and so, rigidity of the rotary member cannot be increased. Under the circumstances, in case where a user has violently operated this small type joystick, the rotary member which is recovered to the neutral position by the coil spring is subjected to a violent force. Particularly, the rotary member will receive much more load at positions near the shaft portions of the operating stick, due to a load from the above and leverage. Then, this load will make the rotary member deformed and remarkably damage durability of the rotary member. This phenomenon will be prominent in case of the small type joystick formed of plastics by molding.